Motor-control system.



R. H. MG'LAIN, MOTOR CONTROL SYSTEM.

APPLICATION FILED AUG.21 1911.

, "1, 1,137, Patented 001i. 15,1912.

34/ Q r F131]. 20 4 1 7 v v Lq ff Inventor- Robert H. McLain,

HisAttorney.

byMMl no a nnr H; new

'-. 'noronrcon-rnon SYSTEM.

' 'To qllwhomzttimay concern:

-B it known that I, Rosana? H.

itl'zeli oflfi the' United States, residing at ncc'tady, county ofSchenectady, State colt-"New York, have. invented certain new i anduseful I Improvements in M'otor-Control v "Systems, ofw'hichthefollowing is'a specification; y I

"Thisinventionrelatest0 means for controlling the operation-of anelectric motor driving part'of amachine in such a manner .Ltha t-"itwillvary tl1e eXte-nt ofits operation I an icorresponde'nce with themovement of some other'element of said machine.

Q with the up'pcrior the lower roll, asthe case Jmay,be,-'inorderthat-"'itmay be rigidly backed upby saidroll and thus be enabled tosustainithe pressure when the platepasses j between it-andthe otherroll. To reduce the thickness of thebillet to that which it is de'sirecl'the plate shall have, the upper roll 1 must be lowered more orless after each pass ,of the plate. This operation, by reducing thespace-between the upper and the lower rollin which the middle roll plays35- .up and down, also necessitates some-- provision by which the meansfor shifting said iniddle roll shall be automatically varied inits'action to correspond with the, lessening r range of movementotsaidmiddle roll. in 40. the mill tow'hich my invention relates, themiddle roll is shifted by an electric motor, running in one direction toraise said roll and inthe other direction to lowerit; As-

'sum ing' that-a given number of revolutions must be made to eflect themaximum shift of "the roll, it is evident that as the'range oi.moven'ient of said roll lessens, so also the number-of revolutions ofsaid motor must lessen. v

The objectof my invention is to effect this result automatically byplacing the motor under the control of the operator who handles the.upper roll. In brief, I employ two-limit switches, one geared to thescrewdown mechanism of the upper roll and the Specification of LettersPatent. "Application men August 21, on. Serial No. 645,167.;

McLAin The invention is especially applicable to middle rollfmoves up ordoWn into, contact .The sketch, Fig. 2,

STATESPATENT clarion, l orsonnnncranv, NEW YORK, Ass lotion TO eminentnLEc'rnIc .co v ranv, AcoRPonArIon or NEW YonK.

Patented Oct. 15,

other to'themiddle roll motor. Tworelays' control contactors whichinturn control the motor circuit. One relay governs the motor when theroll is going up and the other relay when said roll is going down, andwhen both relays are down or up the motor will not run. If only onerelay is up the motor can run, and that relay determines thedirection ofrotation of the motor. The limit switches have their segmentsoverlapping so that for a given number of segments and fingers nearlytwice as many stations or positions can be obtained.

' The invention will be better understood from the following detaileddescription, reference being had to the accompanying drawing, inwhich-,- I

Figure 1 is a diagram of the circuits emt bodymg my system, and Fig. 2is a (liagrammatic sketch of a three-high niill with the limitingswitches and roll-sliiftinginotor.

Referring first to the sketch, Fig. 2, the three rolls 1, 2, 3 are seen.to be arranged in a vertical tier, roll 3 being thelowest and journale'din stationary bearings. The upperroll 1 is arranged to be screwed down,the mechanism illustrated being a simple screw -fl and-hand wheel 5;though in practice more elaborate .mechanism is usually employed.Operatively connected to this sc'rewdown mechanism, whatever its char-.acter may be, is a limit switch 6, preferably in theform of a drumofinsulating material carrying conducting segmentswhich 00- operate withstationary contact fingers as usual. than one revolution during theextreme travel of the upper roll 1.

The middle roll 2 is arranged to move vertically in the space betweenthe rolls 1 and and is shifted by an electric motor T. indicates thisfact by showing the motorconnected by worm gearing 8 to a not 9rotating" in a fixed bearing and meshing with an upright non-rotatablescrew 10 carrying on its upper end a. platform 11. The middle roll isjournaled in boXeswhich slide in vertical guides and the journals orprojections on said boxes are engaged by the hookedends of lovers 12suitably fulcrumed at 13 and carrying Weight 1' 1 which overbalaucestheweight of the roll and rests upon the platform 11. The sketch, showsthis mechanism in a merely illustrative mannenas farl'l'lOlQsQlElbOl'iltQ and suitable mechanismwouldbe used in actualpractice. A second limit switch. 15

rotates in synchronism with the movement of the roll 2 up and down, saidswitch being similar in construction to the switch 6.

roll 2 to move downwardly. Vhen the platform is lowered, the weightfollows it down a 16. The

and raises the roll 2. Whenever the motor runs the switch 15 turns also,making a little less than one revolution during the time that t-he'roll2 is traveling through its greatest range-of movement. The two switchesare electrically connected in such a manner that when they occu y acertain predetermined angular relation the motor circuit will be broken.This relation changes for each station to which the upper roll is adjusted.

Turning now to Fig. 1, the. positive and negative mains appear atX andY, respec tively, controlled by a double-pole switch power circuits areshown by heavier lines than the control circuits, which receive currentfrom the mains X Ythrough the switch 16. The motor 7 is'diagrammaticallyrepresented by the armature A, the commutating pole field coil F and theshunt field coil S, the latter being connected across the mains X Y bythe conductors 17. The upper or screwdown limit switch 6' is shown inthis figure below the other limit switch 15. Switch 6 has one continuoussegment a and a plurality of short segments b, c, 03, etc. eachoverlapping the next so that alternate positions 2, 4, 6, etc., have twosegments available. All the segments are cross-connected. Fingers a, b,0, etc., cooperate with said segments.

Switch 15 has two continuous segments h, z, and a plurality ofinterrupted segments (2 0 d etc. The interruptions cover one positionand are stepped in the opposite direction from the short segments on thescrew-down switch. The ends of adjacent segments. overlap so that theirends occupy the alternate positions 2, 4, 6, etc. The continuous segmenth is connected with all the right-hand portions of the interrupted seg.ments bf, (2", etc., and the continuous segment 2' 18 connected withall the left-hand portions of said segments. Fingers h, i cotivesegments 1), 0 etc. The fingers which coiiperate with the steppedsegments in the screw-down limit switch 6 are connected respectivelywith the fingers bearing the same reference letters which cooperate withthe interrupted segments in the limit switch 15, but inversely; that is,the lowest finger in switch 6 with the highest finger in switch 15, andso on. Finger a of switch 6 is connected by the wire 18 with the main Xthrough the switch 16, and by a branch wire 18 with afinger I in amasterswitch 19: Finger b in switch .15is connectedby wire 20 withanother finger 7c in. said master switch, as well as to finger b 1nswitch 6. Finger h is connected by a wire 21 witha solenoid 22 formingpart of the up relay and finger i is connected by wire 23 with thesolenoid 24 of the down relayr Both solenoids are connected by wire 25with the negative main Y through the switch 16.

l The up relay has an interlock 26 which when down closes on twocontacts27 and when raised on two contacts 28. In a similar manner the interlock29 of the down relay closes on the sets of lower and upper contacts 3031. Contacts 27 are connected respectively by wires 32 33 with thefingers n 0 in the master switch. One" of the contacts 28 is connectedby wire 84 with the finger m in said switch. The other contact 28tactors serve to close the circuit of the motor 7 on both sides of thesame. The two pairs send current from the mains X Y through said motorin opposite directions so it will shift the roll 2 up or down asthe casem( be.

Current coming along the wire-35 tem the up relay passes through aninterlock 41 controlled by the contactor 39, thence through the coils ofthe contactors 37, and

38 in parallel then to the wire 42 and thenegative control conductor 25.When these contactors close, power current flows from contactor 37through the field coil F and armature 'A from left to right and thencethrough contactor 38 to the resistance coils 43 44 Sof which any desirednumber may be used and so on to the negative main Y. When the contactors 37 38 pick up, they also close the interlocks 45 46 in abranchcircuit 35 from .the wire 35 which includes the coil, of the contactor47. The energizing of this coil short circuits the resistance coil 43andcloses an' interlock 48v which controls a branch circuit through thecoil of conw thefield coil F and armature A from righti is reversed.

ftactor-4 9. This shortcircuits the other resi'stlance.il'andputs themotor up to full speed. I lhe interlock l6 h 'asla high resist- 1 fiance holding coil, 50 in a shunt 51' around th'eres stanCeS 43 414:;"and the nterlock 48 'has a lowjres1stance holding 0011 52 in series.Ifwit-h the'power circuit ,Tlicse coils 5O 52 "pre'i'e'nttheirinterlocks from closing until 1 the currentin thepower circuit hasdropped toagiten value. A second interlock 5-4; is opened by"1thecontactor 3'7 when it picks tun thereby opening; a control circuit which"branches from the control conductor- 18 through the wire 55, passest-hrougl'i the interlocks on the contactors respectii ely, thencethrough the actuating 1 coil-' ot thefcontactor 57 and on out to the"negative conductor-25.; The contactor 57 shortcircuits part'of-aresistor 58 which is permanently connected across the terminals of themotor 7. it high resistance holding coilelluinishunt itossaid resistorretards the fcl'osing'otaninterlock (30 which controls a ccntacto-rtil'whoseclosing short circuits the i "motor one. dead shortcircuit. Theresistor '58 sfput; back 111 circuit when the ccntactor BT'p c'hsup andopens the interlock 5st in I? lthecontr'olcircuitfie. 1f the down. re-

.laj 'is the one'whichhas' closechthen current will flowwthroughthe wire36 to the'1nter'- --l'ock 62 controlled by the contactor 3?, and

[l\fill' divide between the contactors 39 and l 1 40. "Whenthese pickupthey close the interlocks G3 ((E-t controlling the, branchcircuit,86""fromthe wire 86 which at the interlock 61- ccnnects with thecircuit 35 and if jcutst'out' thelresistance coils M as before. The-motor will now be running at full-speed, That the current flows throughto-left, so that the direction of the motor Having thus described themotor control and power circuits and the'conncction there- .with; of theup and down relays, I \\-ill"11ow;turn 'to the limit switches 6 15 rand" the master switch-19'. The up re- 'l ay, which causes the motor 7to raise the middle roll connected .withthe right thei down relay beingconnected with the left hand portion thereof. During the re 'ticn to theother in succession, breaking cir cuit at the gaps-in the/segments. Thebutton Z in the 'master switch isalways alive, and the button A: willbecome alive as soon as the fingers a 6 make contact with the segments a7) of the screw-down switch. The operation can best be explained bytaking an example or two. Assume that the middle roll 2 is resting onthe lower roll 3 'i3 5 wi th the upper-r0111 atits-highest position,

remainder the resistor 58, and puts the handor lower portion of theswitch 15:

tation of this switch by the motor 7, the. contact fingers it, etc. passfrom one porthat is, somewhere in the region indicated by the'line 11-.A bill'et has been passed between rolls 1': and 2 and is ready to bep'assedback between 2 and In order to effect a reduction in thethickness of the billet,:the space between rolls 2 and 3 must beless-than that which now exists between rollsl, and 2, and yet roll 2must be backed up by the upper, roll to give it rigidity. This-meansthat the upper roll must be lowered by an amount equal to the .desiredreduction in thethickness of thebillet. Moreover, the motor attached tothe platform 11 must lower it -tar enough to let the counterweight .L-llift the roll into firm contact with the lowered upper roll but muststopv as soon as the platform has dropped slightly away from saidcounterweight. Assume that an attendant screws downthe upper roll. intothe region indicated bythe dotted line 9. T This operation also rotatesthe switch Gj-until the tier of fingers. a, ,6, etc., register with theterrito ry marked 9 in Fig. 1. -The finger a will be on segment a andtheiingcr f on segmentf, all other fingers of this switch being out ofcontact with" their segments. The middle roll being in its lowestposition, its switch 15 will stand in the position shown. Current willthen fio-w from the switchlG by way of the wire 18 to the finger a,segment a, segment f, linger f, finger f -right-hand part of segment fsegment h,,finger h, wire 21, relay coil 22", and wire to switch 16. Theup relay will at once pick up, causing the interlock to bridge thecontacts 28. An at tendantfnc-w shifts the master switch until segment2) rests on buttons Z, m, and 0. This sends current from the switch 16by way of wires 18', 18, button l,.segment 2), button m, wire 34,contacts 28, contacts 30, and wire 35 to the coils of the up contact-ore37 38, starting the motor, as beforedescribed', to let the" roll rise.The closing of the switch 16 has placed the motor armature A and fieldcoil F on a dead short circuit by cutting out the resistor 58. Butthepicking up of the power cont-actor 37 breaks the control circuit atthe-interlock. 54- and allows the contactors 57 (31 to open again, thusrestoring the resistor 58 to the shunt around the armature and seriesfield and forcing the power current to flow through said armature. andfield.

As soon asthe motor commences town,

the counterweight 1st begins to lift the roll 2, and the motor alsorotates the switch 15.

-lVhen the break, in the segment f arrives contactors 87 and 38 and cutofl the power current. The circuit 55 is also reestablished, cutting outthe resistor 58 which was in C11- vcuit while the meter was running, andClos ing the motor armature on a short circuit, containing noresistance, so that, running by momentum, said motor acts as a generatorand stops almost instantly, with the platform 11 a short distance belowthe counterweight 14. The billet is now passed through between themiddle roll and the lower roll,

after which the middle roll must be brought down to its former positionon the lower roll, and the upper roll must be lowered again to furtherreduce the space between it and the lowered middle roll to effectanother reduction in the thickness of the billet.

A uick lowering of the middle roll can be e ected by throwing over themaster switch 19 until the segment 1 rests on the buttons 70,1 and n.This sends current from the switch16 by way of the wires 18 18,

J button 1, segment 1*, button A, wire 20, finger platform 11 andlowering theroll 2 and also rotating the switch 15 backward until thefirst or lowest position is reaehechwhen the relay circuit is broken atthe'finger b the down relay drops, and the motor stops as before withroll 2 resting on roll 3. The screw-down operator now screws down theupper roll to the desired new position; say somewhere in the territoryof the station 8;

' the switch 6 turning to said position at the same time. Both relaysare down and no current can flow to the motor until an attendant throwsover the master switch to return segment 7) to its position on buttonsZ, m and 0. Current then passes from the main X by way of the switch 16'to wire 18, finger a, segment a, segments 0- f, fingers e f, fingers e fand the right hand portions of segments 6 f segment h, finger h, andwire 21 to the up relay coil 22. Again the motor starts to let the roll2 come up toward the eighth station, and the switch 15 turns with it.The finger a arrives at the break in segment etwhen it reaches theseventh position, but current continues to flow to the relay throughfinger f until the eighth position is reached. The finger c has nowpassed over upon the left hand portion of its segment 0 so that althoughthe up relay is still energized through the segment f'-, yet currentwill flow from finger e to the segment 2', finger 2', wire 2?, andsolenoid 24, so that the interlock 29 will be opened and will break thecontrol circuit 35 at contacts 30 and stop the motor. Both relays arenowin their raisedpositions and yet the effect is the same as when bothwere down that is, the motor cannot run. The

middle roll is now shifted to its original po-' sition again by throwingover the master switch tobring the segment 1 into service. The relaysare both raiscc, but the current by way of the button a will energizethe down contactors as before. The down relay will drop when the switch15, turning with the middle roll, arrives at position 1, and the finger6 runs. ofi' its segment b The up relay still -remains energized throughthe fingers e, f, e 7. Now if the operator screws down roll 1 to a newposition, the fingers e, f may slide off their segnients, but thecircuit of the relay coil 22 will be maintained by other fingers closingvon their segments before a f" open. \Vhen the upper. roll and theswitch 6 arrive at the new position and the plate has made the upperpass, the operator of the master switch 19 merely throws it over tobring segment ;0 into service, which will send current through the upcontrol circuit 35, and lift the middle roll to the position requiredfor the lower pass. In this way, the upper roll can be graduallylowered, and after each upper pass of the plate the middle roll willlift just far enough to come into firm contact with the upper roll,ready for the lower pass. If the motor overruns at either end of itstravel no harm will be done, owing to the loose contact of the platform11 with the weight 14 at one end of the levers 12, and the similarconnection of the open hooks at theother end of said levers with thejournal boxes ot the middle roll.

In'casc the middle roll has been liftedand the screwdown operatorproceeds to screw down the upper roll ant thereby push down the middleroll also, it IS desirable that the motor be started to cause theplatform to. follow up the weight 14. Both relays are down. The limitswitches stand at say position 9. hen switch 15 moves to the nextposition (8) finger (2 will make contact with its segment 6 and willsend current-to finger.

a which is resting on the lefthand'iportion of the segment" 6 This Wlllcause the down relay to pick up and close the cirg cult from the button0 in the master switch to the contacts 27 bridged by the interlock. 20,contacts 31, and the down control cir-. cuit 36. The roll 2 willtherefore be dropped by the motor at-the same rate of speed that theupper roll is screwed down. If, on the other hand. the operator hadscrewed the upper roll upwardly while the middle roll was in contactwith it, the up relay would have been energized again through segment 7,the connected fingers .{7 g and the segment so that the roll 2 wouldhave followed up the upper roll.

3 tion of said motor,'a' relay controlling each In accordance with theprovisions of the I patent statutes, I have, described the prin ciple ofoperation of my invention together with the apparatus which-I nowconsider to represent the best; embodiment thereof; but

I desire to have it understood that the apparatus shown is onlyillustrative, and that the invention can be carried out by other What Iclaim as new and desire to secure thereby, a limit switch movingsynchro- ".nou'sly with saidv element, a second limit switch. controlledby an attendant, and a I master-switch cont-rolled by an attendant 2;The combination with an electric mo- 3 tor, of a movable machine elementactuated thereby, contactors' controlling the power circuit,- of saidmotor, relays controlling said contactors, and ,two limit switchescontrolling said'relays, one limit switch being controlled by anattendant and the other moving synchronously with said moving element.

The combination with an electric motor, of a movable machine elementactuated thereby, two or more contactors or sets of contactorscontrolling the direction of rota-,

' contactor or, set-thereof, and each relay controlling both controlcircuits, said circuits beingop'en when] both'relays are in either,theirupper or lower positions, and limit switches controlling saidrelays.

1 4. The conibination with a three-high rolhng mill, of an electricmotor for ralsing and lowering the middle roll, u d down contactorscontrolling the power circuit of said motor, up and down'.'relaysboth'controlling the two control cir- 9 middle roll, saidlintit switches controlling said relays.

- cuits of said contactors, alimit switch moving with the verticaladjustment of the upperroll, and a limit" switch moving with the 5...The combination with .a three-high rolling mill, of an electric motorforv raising and lowering'the' middle roll, up and F down contactorscontrolling the ower c1r cu1t of said mot0r," up and own J relays bot-hcontrolling the two control cir- I cuits of'said contactors, a limitswitch mova 7 upper roll, and a limit switch moving with ing with thevertical adjustment of the rolling mill, of an electric motor forraising and lowering the middle roll, means whereby the lift of saidrollis controlled by the position of the upper roll, and meansfo-r causingsaid middle roll, when lifted, to folloivl' the changes in position ofsaid upper ro 8. The combination with an electric motor, of two relayscontrolling respectively its two directions of rotation, and two limitswitches controlling said relays, said switches having a plurality.otfingersand cooperating segments, and said segments overlapping attheir ends. so that a greater number of limit positions is afforded thanthe number of segments.

9. The combination with an electric motor of two controllers in circuittherewith, one having a plurality of stepped and overlappingsegments,and the other having a pluralityof interrupted segments, theinterruptions being stepped.

10. The combination with an electric motor of two controllers in circuittherewith, one having a plurality of stepped and overlapping segments,and the other. having a plurality of interrupted segments, theinterruptions being stepped, a group of fingers for each controller, andconnections between corresponding fingers in said groups 11. Thecombination with an electric motor,'of a plurality of contactors forcontrolling the same, a'pair of relays each having an up and a downposition for con-' trolling said contactors, and means whereby saidmotor circuit is opened when both relays are in either the up or thedown position.

In witness'whereof, I have hereunto set my hand, this 18th day of August1911.

ROBERT H. MoLAIN.

Witnesses:

' BENJAMIN B. HULL,

HELEN ORFORD.

copies of this patent may be obtained for five cents each, by dressingthe commissioner of Patents,

y Washington, D. O."

